pysdif 0.1.0

pysdif is a Python library that allows to read and write any kind of SDIF file, to define new kinds of frames and matrices and to read and write metadata.<br /><br />The matrices read from a sdif file are exposed as numpy arrays.<br /><br />It exposes both a low level and a high level interface.<br /><br />The low level interface for reading and writing sdif files mirrors the sdif library quite transparently so that the example files and utilities using it can be directly translated with it. In particular it does not create any intermediate objects, even the data of the matrices is a numpy array mapped to the c array read from disk, so no allocation takes place. Whereas this makes for very fast code, one has to take care to copy the data if it will be used longer, since by the time a new matrix is read this data is no longer valid.<br /><br />to read for ex. 1TRC format:<br /><br />import pysdif<br /><br />sdif_file = pysdif.SdifFile('filename.sdif')<br />sig1TRC = pysdif.str2signature("1TRC")<br />while not sdif_file.eof:<br /> sdif_file.read_frame_header()<br /> if sdif_file.frame_numerical_signature) == sig1TRC:<br /> print sdif_file.time<br /> for n in range(sdif_file.matrices_in_frame):<br /> sdif_file.read_matrix_header()<br /> if sdif_file.matrix_numerical_signature == sig1TRC:<br /> data = sdif_file.get_matrix_data()<br /> # data is now a numpy array but you must copy the data if<br /> # you intend to keep it after you have read the matrix.<br /> # One you read a new matrix, this data will be no longer valid<br /> print data<br /><br />a more natural way:<br /><br />from pysdif import SdifFile<br />sdif_file = SdifFile('filename.sdif')<br />for frame in sdif_file:<br /> if frame.signature == "1TRC":<br /> print frame.time<br /> for matrix in frame:<br /> if matrix.signature == "1TRC":<br /> print matrix.get_data()<br /><br />the frames and the matrices resulting from the iteration are only guaranteed to be valid as long as no new frames and matrices are read<br /><br />to write a SdifFile:<br /><br />f = SdifFile('new_sdif.sdif', 'w')<br /># these are optional<br /># add some metadata<br />f.add_NVT({<br /> 'name' : 'my name',<br /> 'date' : time.asctime(time.localtime())<br />})<br /># define new frame and matrix types<br />f.add_frame_type('1NEW', '1ABC NewMatrix, 1FQ0 New1FQ0')<br />f.add_matrix_type('1ABC', 'Column1, Column2')<br /># now you can begin adding frames<br />frame = f.new_frame('1NEW', time_now)<br />frame.add_matrix('1ABC', array([<br /> [0, 1.2],<br /> [3.5, 8.13],<br /> ...<br /> ]))<br />frame.write()<br /><br /># say we just want to take the data from an existing<br /># sdiffile, modify it and write it back<br />in_sdif = SdifFile("existing-file.sdif")<br />out_sdif = SdifFile("outfile.sdif", "w")<br />out_sdif.clone_definitions(in_sdif)<br />for in_frame in in_sdif:<br /> if in_frame.signature == "1NEW":<br /> new_frame = out_sdif.new_frame("1NEW", in_frame.time)<br /> in_data = in_frame.get_matrix_data() # we know there is only one matrix<br /> # multiply the second column by 0.5<br /> in_data[:,1] *= 0.5<br /> new_frame.add_matrix('1ABC', in_data)<br /> new_frame.write()<br /><br />#md5=d9129a6bd3158365f5132a075a9e1274

Requirements:	No special requirements
Platforms:	*nix, Linux
Keyword:	Array,  Data,  Date,  Define,  Files,  Frame,  Frames,  Level,  Library,  Longer,  Matrices,  Matrix,  Name039,  Numpy,  Print,  Pysdif,  Quot Trcquot,  Sig Trc,  Valid,  Write
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